The present invention relates generally to medical treatments. More specifically, the present invention relates to bicarbonate-based solutions for use during dialysis therapies, such as continuous renal replacement therapies.
A variety of different medical treatments are known and used to treat critically ill patients for acute renal failure (ARF) which is typically associated with multiple organ failure syndrome in intensive care settings. For example, traditional dialysis therapies, such as hemodialysis and peritoneal dialysis, are commonly used to treat ARF.
However, because traditional dialysis therapies are known to have limited use with respect to the treatment of critically ill patients for ARF, the use of continuous renal replacement therapy in favor of traditional dialysis therapies has increased, particularly in intensive care settings. In this regard, a number of possible advantages with respect to CRRT in comparison to traditional dialysis therapies have been recognized.
A foremost advantage is the potential to effectively avoid, or at least minimize, cardiovascular instability. In this regard, CRRT, in general, is a slow and continuous therapy that does not include rapid shifts in blood volume and electrolyte concentration due to the removal of metabolic products from blood as compared to traditional forms of dialysis therapy, such as hemodialysis. Examples of continuous renal replacement therapies include continuous arteriovenous hemofiltration, continuous arteriovenous hemodiafiltration, continuous venovenous hemofiltration, continuous venovenous hemodiafiltration, slow continuous ultrafiltration and continuous ultrafiltration periodic intermittent hemodialysis.
In general, CRRT is a convective blood cleansing technique that utilizes a patient's blood pressure as the primary driving force for ultrafiltration. During CRRT therapy, blood typically flows through a hemofilter such that a transmembrane pressure gradient between the blood compartment and the ultrafiltrate compartment causes plasma water to be filtered across the highly permeable membrane. As the water crosses the membrane, it can convect small and large molecules across the membrane and thus cleanse the blood.
An excessive amount of plasma water is also removed during continuous renal replacement therapy. In order to maintain a proper water balance in the patient's body, fluid must be substituted continuously by a balanced electrolyte solution (replacement or substitution fluid). The substitution fluid can be infused intravenously either into the arterial blood line leading to the hemofilter (predilution) or into the venous blood line leaving the hemofilter (post dilution).
Typically, commercially available replacement fluids are lactate-based solutions. However, the physiological buffer bicarbonate is preferred over lactate in patients with multiple organ failure which is typically associated with ARF. In this regard, the metabolic conversion of lactate to bicarbonate is not required prior to metabolic action thus eliminating undesirable effects due to the conversion process of lactate to bicarbonate.
Further, it is common practice among intensive care physicians to manually prepare solutions buffered with bicarbonate extemporaneously. This is typically carried out by adding the prepared bicarbonate solution to an existing sterile solution to form the bicarbonate-based solution prior to administration to the patient. For example, it is known to add bicarbonate to an acidic electrolyte concentrate solution which is in direct contact with administration tubing connected to the patient prior to administration thereof to the patient. It is also common practice to manually inject other electrolytes, such as potassium chloride, directly and separately into the bicarbonate-based solution prior to administration.
However, the physical handling due to the initial preparation of a bicarbonate solution, subsequent addition thereof to another solution and manual injection of other components to form the resultant bicarbonate-based solution prior to administration may be too tedious and time-consuming to adequately address the time-sensitive nature of responding to ARF in an intensive care setting. This practice may also necessarily cause the bicarbonate to degrade into a volatile carbon dioxide gas and a carbonate ion, which then can react with calcium and magnesium ions in solution to undesirably form precipitates, thus impeding proper administration. Further, the potential of bacteriological contamination of the bicarbonate-based solution is great unless strict aseptic techniques are followed during preparation.
A need, therefore, exists to provide improved bicarbonate-based solutions that can be effectively administered during continuous renal replacement therapy to treat ARF, particularly as administered to critically ill patients in an intensive care setting.